The present invention relates to the field of chemical and biological analysis and more specifically to the use of Raman and fluorescence imaging spectroscopy to quickly identify chemical and biological agents.
Terrorist deployment of chemical and/or infectious biological agents as weapons of mass destruction threatens the welfare of the human populace. Public concern has grown, especially in our nation, as terrorist uses of biothreat agents, such as Anthrax, become reality. Nightmare images of tens of thousands of infected and dying innocent victims strike fear in the hearts of nearly everyone. Biological and chemical warfare is significant, not only in lives lost, but also in the cost to the US economy. The Centers for Disease Control estimates that the loss of 100,000 lives will have a $29 B economic impact. The mass destruction potential of Biological Warfare Agents (xe2x80x9cBWAsxe2x80x9d) and Chemical Warfare Agents (CWAs) is thought by many to be comparable to or even greater than that of nuclear weapons. Nuclear weapons have the potential to affect a finite area, albeit very large, and the use of such weapons is immediately obvious after the fact. BWAs and CWAs, on the other hand, have virtually no boundaries and have the potential to spread silently and unchecked through populations far from ground zero. Likewise, technology to rapidly detect and quantify very low levels of radioactive contamination is widely available. Unfortunately, such technology for BWAs and CWAs at similar levels is not definitive, not widely available and in many cases, is not very rapid.
The psychological impact of this type of threat is also very significant. The public is becoming increasingly aware of new, emerging pathogens. Fears over the unseen nature of BWAs and CWAs make for a very effective terrorism weapon in and of itself. In addition to perception, there is a very real threat due to incredible advances in biotechnology. It is now possible to alter the most virulent bacterium or virus and to increase both its pathogenicity and resistance to conventional therapy. The molecular biology revolution has now been underway for more than three decades, and the sheer number of persons with technical expertise to potentially create such weapons of mass destruction has consequently increased. In this age of advanced global travel, the likelihood of rapid dissemination of any type of BWA worldwide in a very short period of time is high, and the general public is well aware of this fact.
Conventional means of identifying pathogens using biology tools such as specific antibodies, genetic markers or propagation in culture are fundamentally slow and require hands-on manipulations. Furthermore, as new BWAs and CWAs are engineered, these conventional tools are likely to become less and less effective. As the use of BWAs and CWAs by terrorists becomes a reality, there is an increasing need to develop tools that can rapidly and accurately detect and classify these agents at a molecular level without coming into contact with them. These tools are needed to help expand our understanding of the biological and chemical basis of such warfare agents and the potential impact on the human body. Furthermore, the knowledge gained through such molecular analyses helps identify new targets for therapeutic and preventative agents.
A spectroscopic imaging system, also described as a chemical imaging system, employing Raman, fluorescence, UV-visible reflectance/absorption and/or near-infrared (NIR) reflectance/absorption spectroscopic techniques for characterization of BWAs and CWAs is disclosed.
In one embodiment, Raman microscopic imaging spectroscopy and/or fluorescence microscopic imaging spectroscopy can be used to detect, classify, identify and/or visualize BWAs, CWAs and non-threatening compounds. Microscopic imaging spectroscopy detects, classifies and identifies sub-micron size particles, including single bacterium. In addition, Raman microscopic imaging spectroscopy can perform sub-micron size particle detection, classification, identification and visualization of BWAs and CWAs in the presence of non-threatening xe2x80x98maskingxe2x80x99 compounds when appropriate data analysis techniques are applied.
In another embodiment, fluorescence and Raman macroscopic imaging spectroscopy can be used to detect, classify, identify and/or -visualize BWAs, CWAs and non-threatening compounds. These macroscopic imaging techniques can perform sub-millimeter size particle detection, classification, identification and visualization of BWAs and CWAs (i.e., agglomerated bacteria and endospore detection and identification). In addition, fluorescence and Raman macroscopic imaging spectroscopy can perform detection, classification, identification and visualization of BWAs and CWAs in the presence of non-threatening xe2x80x98maskingxe2x80x99 compounds when appropriate data analysis techniques are applied.
In an another embodiment, Raman fiber optic dispersive spectroscopy can detect, classify and/or identify BWAs, CWAs and non-threatening compounds. Moreover, Raman fiber optic imaging spectroscopy can detect, classify, identify and/or visualize BWAs, CWAs and non-threatening compounds when appropriate data analysis techniques are applied.
In order to provide faster real-time analysis, Fiber-Array Spectral Translator (FAST) dispersive spectroscopy is used for rapid detection, classification and identification of BWAs, CWAs and non-threatening compounds. In addition, Fiber-Array Spectral Translator (FAST) imaging spectroscopy can be used for rapid detection, classification, identification and visualization of BWAs, CWAs and non-threatening compounds when appropriate data analysis techniques are applied.
The systems described above are applied in a variety of modes. The system is applied as a laboratory or transportable field Raman microscope such as ChemImage""s FALCON Raman microscope outfitted with ChemImage""s Simultaneous Imaging and Spectroscopy Apparatus. The system is also applied as a UV/Vis/NIR fluorescence, Raman, or UV/Vis/NIR/Mid-IR absorption/reflectance macroscope system such as ChemImage""s CONDOR Macroscope. Alternatively, the system is applied as a laboratory or field fiberscope such as ChemImage""s RAVEN endoscope. In addition, the system is applied as a laboratory or field Fiber-Array Spectral Translator (FAST) probe. Each of the modes of application are used separately or in combination with one another to achieve the desired speed and results.
Spectroscopic imaging techniques are applied to sensors designed to detect, classify, identify and/or visualize BWAs, CWAs and non-threatening compounds in ambient air. A schematic of such a sensor is shown in FIG. 1. The vacuum created by an air-sampling pump pulls the ambient air through the sample inlet and through the filter. Filter materials could include porous polypropylene or cellulose, in disk or roll form. Particulates in the air sample are trapped on the surface of the filter medium and are held in the field of view of the spectroscopic imaging system. The source, chosen specifically for the type of molecular spectroscopy being used, illuminates the trapped particles and induces either Raman or fluorescence emission from the sample. The imaging detector measures the spatial distribution of emitted light at a series of wavelengths and creates the data file used for further analysis. The inlet to this imaging detector can either be an imaging optical fiber or conventional optics. Advanced chemometric techniques along with image analysis routines are used to detect, classify, identify and/or visualize BWAs, CWAs and non-threatening compounds.
The system can be automated through the use of robotics or combined macro/micro instrumentation in order to target BWAs, CWAs and non-threatening agents. Using laser ablation and/or chemical ablation, the system can be automated to eradicate BWAs and CWAs post-targeting
A variety of data processing procedures can be used with the system. A weighted spectral image data subtraction routine can be used to suppress contribution from microscope slide. Alternatively, multivariate image analysis involving principal factor analysis and subsequent factor rotation can be used for differentiation of pure molecular features in BWAs, CWAs and non-threatening xe2x80x98maskingxe2x80x99 compounds.